Last year, I posted an article on this blog
How
to keep your eyes healthy while working on computer long hours?,
which drew much attention from the blog readers. Per one of the visitors’
request, I am would like to continue investigation the topic of the proper
ergonomic arrangement, while working on the computer. Impact on your eyes is
just one of the negative factors, you are experiencing, while working on your
PC for long hours. How to minimize it and make your work environment as safe as
it can be?
Overview
Average computer
user performs 50,000 to 200,000 keystrokes a day. Making so many repetitive
movements can contribute to the related health issues, and even lead to the significant
health impairment in some cases. Uncomfortable seating and awkward wrist
movements can also add to overuse injuries. These injuries take time to
develop, and extensive computer use can hasten them. Symptoms may include
numbness, soreness, pain, fatigue, discomfort and eyestrain.
What is Repetitive Stress Injury?
Repetitive Stress Injury is a kind of catch all phrase for
many conditions. Carpal Tunnel Syndrome, Tenosynovitis / DeQuervain's Syndrome,
Tendonitis, Thoracic Outlet Syndrome, Trigger Finger, Myofascial Pain Syndrome
and Chronic Sprain / Strain are some of the actual diagnosis that be diagnosed among
computer users.
All of these conditions are serious and in many cases can
cause great pain, permanent disability and sometimes loss of employment.
Repetitive Stress Injuries (RSI) occur from repetitive
movements involving a specific set of muscles and joints. RSI injuries are the
result of an accumulation of stress and strain that causes irritation,
inflammation, and eventually pain or other disability. Initially, RSI affects
the soft tissues of the involved joint(s). Soft tissues include muscles,
nerves, ligaments and tendons. However, if left untreated for long periods of
time, the involved joint can become arthritic and form bone spurs resulting in
permanent damage to the joint.
The constant demand of keyboarding and mousing combined with
the postural stress of confinement in an office chair with one's neck and back
held in prolonged fixed positions has resulted in an epidemic of injuries that
includes hand pain, wrist pain, arm pain, neck pain, back pain and shoulder
pain.
Common Symptoms
The brief list of
the common symptoms, associated with RSI, caused from computer use:
- Tightness,
discomfort, stiffness, soreness or burning in the hands, wrists, fingers,
forearms, or elbows
- Tingling,
coldness, night pain or numbness in the hands, especially around the base
of the thumb
- Clumsiness
or loss of strength in the hands
- Pain
in the neck, shoulders, wrists, hands or back that is associated with
using the computer
Computer Ergonomics
The work place is often seen as the place with the lowest
risk of injury; as opposed to injuries from outdoor activities like basketball,
tennis, skydiving etc. This could not be further from the truth. Musculoskeletal
disorders that cause great discomfort can develop if the proper ergonomic
guidelines are not taken into consideration.
Desktop Ergonomics
If you use a desktop, these are the computer ergonomics
factors to consider such as visibility, chair, monitor, desk, keyboard, mouse,
for maximum ergonomic benefit.
Visibility
1. Incandescent light is preferred over fluorescent lighting
(less strain on the eyes)
2. Glare on the screen and the rest of the environment is
not recommended
3. Task lighting is not recommended for computer use.
Chair
The most suitable chair is the one that allows the user to
adjust to his/her ergonomic sweet spot. Ensure the following,
1. Backrest or ergonomic back supports
provides support for your lower back (lumbar area).
2. Seat width and depth accommodate the
specific user (seat pan not too big/small).
3. Seat front does not press against the back of your
knees and lower legs (seat pan not too long).
4. Seat has cushioning and is rounded with a
"waterfall" front (no sharp edge).
5. Ergonomic-Arm-rests, if used, support both
forearms while you perform computer tasks and they do not interfere with
movement.
6. Thighs have sufficient clearance space between the
top of the thighs and your computer table/keyboard platform (thighs are not
trapped).
7. Legs and feet have sufficient clearance
space under the work surface so you are able to get close enough to the
keyboard/input device.
8. A Footstool is used if your feet are not touching
the floor, when your knees at a somewhat right angle
Monitor
1. Top of the screen is at or below eye level so you
can read it without bending your head or neck down/back. Place the center of
the screen at a 15 degree down angle from your eyes
2. User with bifocals/trifocals can read the screen without
bending the head or neck backward.
3. Monitor distance as far away as possible but still
allows you to read the screen without leaning your head, neck or trunk forward/backward.
4. Monitor position is directly in front of you so
you don't have to twist your head or neck.
5. Glare (for example, from windows, lights) is not
reflected on your screen which can cause you to assume an awkward posture to
clearly see information on your screen. Position the monitor to minimize glare
by placing it at a right angle to light sources or windows.
6. Set the refresh rate at a minimum of 70 Hz to limit
flicker.
Desk
Sufficient space is allowed to easily read hardcopy material
close to you while working with the computer.
Keyboard
1. Keyboard/input device platform(s) is stable and large
enough to hold a keyboard and an input device.
2. Wrists and hands do not rest on sharp or hard edges.
3. The keyboard should be positioned at or below the elbow
to keep the wrist aligned with the forearm or at a slightly negative angle.
Keyboard tray is recommended for such purposes.
4. Keep your fingers relaxed while typing. Use a soft touch
on the keyboard instead of pounding keys with unnecessary force. Relax your
fingers and hands between bursts of typing.
5. Familiarize yourself with keyboard shortcuts for
applications you regularly use (to avoid overusing the mouse).
Mouse
1. Input device (mouse or trackball) is located right next
to your keyboard so it can be operated without reaching and at the same level
as the keyboard.
2. Input device is easy to activate and the shape/size fits
your hand (not too big/small).
3. Wrists and hands do not rest on sharp or hard edges.
When the mouse is being operated at a distance that makes
the operator reach, the shoulder extends forward and the shoulder blade abducts
(rotates forward). This position stretches the muscle groups that connect the
medial portion of your shoulder blade to your spine and the superior portion of
your shoulder blade to your neck. In the short term, this stretch aggravates
the affected muscle groups causing spasm, fatigue, headaches and stiffness in
the neck and shoulder. In the long term, this position creates a condition
called a "stretch weakness" resulting in muscular imbalance, trigger
points and chronic variations of the conditions listed in the prior sentence.
Placing the mouse too far away, too low, or too much on one
side can cause shoulder, wrist, elbow, and forearm discomfort. When the
operator is forced to reach for the mouse, his / her body weight shifts forward
and ultimately results in weight bearing stress on the extended arm. Spending
prolonged periods of time leaning on an extended arm is an unnatural and
destructive posture that will eventually lead to the development of a
repetitive stress syndrome; likely resulting disorders would include tendonitis
of the wrist, elbow or shoulder.
Computer Posture
Get a suitable, height adjustable, chair.
- Sit
far back in with your back touching the back support.
- Adjust
the height of your chair by its function such that when you 'type' your
elbows are at a right angle.
- Check
your feet. Make a right angle with your knees. Are your feet touching the
ground? If not, get a foot stool to adjust your foot rest until your knees
make a right angle like your elbows.
- Look
straight and your computer monitor screen should be at eye level or
slightly under eye level to prevent neck strain.
- Adjust
your monitor's height.
- Practice
good posture; do not slump in your seat.
The body is not designed to sit still, even in correct
position, for long periods of time. Some individuals find that using a computer
extensively can cause discomfort, so regular pauses are not a waste of time.
Change your seated position occasionally, stand up or stretch whenever you
start to feel tired. Depending upon your work and environment, you may want to
take breaks. It is generally recommended regular breaks from working at your
computer for a few minutes at least once an hour.
Basic stretching exercises can help keep limber the joints
and muscles you use when you sit at a computer. Some examples:
- General:
Stand up and stretch your arms over your head.
- Neck:
Tilt your head to one side (ear to shoulder); hold; relax; repeat on other
side.
- Shoulders:
Slowly bring shoulders up to the ears and hold briefly.
- Wrist:
Hold arm straight out in front of you; pull hand backwards with other
hand, then pull downward; hold; relax; repeat with other hand.
